There has been proposed in U.S. Pat. No. 4,980,608 an electric motor rotator for Christmas tree ornaments which includes a small-size synchronous electric motor which is adapted to plug into a lamp socket of a string-set of series connective decorative incandescent lamps so as to utilize the output of the motor to rotate ornaments and light devices.
The motor includes a cup-shaped rotor having an annular magnetic medium deposited on the inner wall of the cup on either side of which inner and outer stators are disposed which interact electrically with a small AC excited coil to cause the rotor to rotate at the synchronous frequency. Even through such a design of motor would, once started, run in one direction or the other this is no particular problem because it is a simple matter to include a so-called "no-back" device to cause the motor to run in a predetermined direction each time it is energised as is shown, for example, in FIG. 5 of U.S. Pat. No. 4,980,608.
The disadvantage of the motor rotator disclosed in U.S. Pat. No. 4,980,608 is that it is of very low power which limits the range of movement which can be achieved utilising the device. This is because the coil is relatively small and magnetic medium is deposited on the inner wall of a cup-shaped rotor such that rotor density is low. Another disadvantage is that a lightweight rotor is, by definition, not particularly rugged and there is the possibility that damage may occur to the motor in the event that the novelty item were to fall.
It is an object of the invention to provide an apparatus for moving an object which alleviates this disadvantage.
The present invention is derived from the surprising realisation that if a large, solid magnetic rotor is provided which is cooperable with electrically energised and relatively long stators then a correspondingly large coil may be used even if it is axially displaced relative to the rotor and, with such construction, the combination provides greatly increased power relative to the motor described in U.S. Pat. No. 4,980,608 for the same diametric size.